Significant advances in the development of genetically engineered mice lacking or over-expressing specific proteins has proven to be a powerful research tool. As described in this SCOR proposal, a number of interesting transgenic and gene "knockout" models will be developed to explore the role of specific enzymes and proteins in the physiology and pathophysiology of the cardiovascular system. The mouse cardiovascular Physiology Core will assist with the characterization of the mouse models. This Core will provide rigorous physiologic evaluation of mouse models including; 1) characterization of the structure and function of the heart and great vessels using trans-thoracic echocardiography, 2) cardiovascular hemodynamic measurements of the mouse circulatory system using open- and closed-chest cardiac catheterization, 3) identification and characterization of cardiac rhythm disturbances in mice using ambulatory telemetric electrocardiographic monitoring, and 4) to evaluate the responses to short-term and long-term exercise studies in mice. The Mouse Cardiovascular Physiology Core will accomplish these goals in dedicated space within the Clinical Sciences Research Building at Washington University School of Medicine. It is anticipated after the evaluation of the mouse models developed in this proposal will identify cardiovascular abnormalities relevant to the pathogenesis of pediatric cardiovascular disease.